TITLE:
Follicular Occlusion Disorders in Patients with Crohn’s Perianal Disease and the Relationship to Fistulizing Phenotypes
AUTHORS:
Muhammad Hassan, Yash Jani, Kostandin Valle, Ngozi Okoye, Sarah Kazemeini, Liza Yusem Carstens, Corinne Rutkowski, Kelly Frasier
KEYWORDS:
Crohn’s Disease, Perianal Fistulizing Crohn’s Disease, Follicular Occlusion Disorders, Hidradenitis Suppurativa, Inflammatory Bowel Disease, Fistula Complexity, Epithelial-Mesenchymal Transition, Microbiome, Immune Dysregulation, NOD2 Gene, TNF-Alpha, IL-17, IL-23, Genetic Predisposition, Multidisciplinary Management, Perianal Sepsis, Chronic Inflammation, Cutaneous Manifestations
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.14 No.3,
March
5,
2026
ABSTRACT: Background and Objectives: Perianal fistulizing Crohn's disease (pCD) is a challenging phenotype, often associated with significant morbidity and reduced quality of life. Follicular occlusion disorders (FODs), such as hidradenitis suppurativa (HS), share pathogenic mechanisms with CD, potentially influencing disease severity and treatment outcomes. This review aims to investigate the association between FODs and perianal fistulizing CD, exploring the underlying pathogenic mechanisms and the impact on fistula complexity and treatment strategies. Methodology: A comprehensive literature review was conducted, examining studies reporting on the prevalence, clinical characteristics, and pathogenic mechanisms linking FODs and perianal CD. The search included studies focusing on genetic predisposition, immune dysregulation, the role of the microbiome, and epithelial-mesenchymal transition (EMT). Studies assessing the impact of FODs on fistula complexity, treatment outcomes, and diagnostic and management strategies were also included. Results: The prevalence of FODs, particularly HS, appears to be higher in CD patients with perianal involvement. Shared genetic factors, such as mutations in the NOD2/CARD15 gene, and common inflammatory pathways involving TNF-α, IL-17, and IL-23 may contribute to the co-occurrence of these conditions. Alterations in the gut and skin microbiome, as well as the involvement of EMT, further contribute to the pathogenesis of both CD and FODs. The presence of FODs may increase the risk of developing fistulizing perianal CD and influence fistula complexity and severity. Effective management requires a multidisciplinary approach, including medical therapies targeting inflammation and surgical interventions to address perianal sepsis. Conclusion: Follicular occlusion disorders, especially HS, exhibit a notable association with Crohn’s disease, particularly in patients with perianal involvement. Shared pathogenic mechanisms, such as genetic predispositions, immune dysregulation, microbiome alterations, and epithelial-mesenchymal transition, underpin this relationship. The co-occurrence of FODs and perianal CD can significantly impact disease severity, quality of life, and treatment outcomes, necessitating a multidisciplinary approach to diagnosis and management. Future research should focus on elucidating the specific genetic and environmental factors that contribute to this association, as well as developing novel therapeutic strategies that target shared pathogenic pathways.